Is there a proper way to have an "ORDER SAMPLE" or "ADD SAMPLE TO CART" button next to the "ADD TO CART" button for products in Woocommerce? I'd rather not make it a product variant or separate product all together as it would still give the customer the ability to order more than one.

Rather than putting up disclaimers and warnings, I'd rather not have to refuse orders because the system allows multiples of one sample, instead of some kind of automated process.

There is a checkbox for this on the product page, Inventory tab: "Sold individually (Enable this to only allow one of this item to be bought in a single order)". Unfortunately a customer could still come round again to order more.

It would be a non-trivial development job to write code to inspect all previous orders to see if the current customer has previously ordered the current sample.